Setting and triggering device for thermal relay

ABSTRACT

A thermal relay designed to control the power supply circuit of a contactor, said thermal relay comprising movable contacts cooperating with stationary contacts, a triggering slide released by thermoelements for displacing the movable contacts to open the circuit in case of excessive current flow and a hand control, controlling the slide and the movable contacts for opening or closing the circuit. The slide cannot be reset in proper position for closing the circuits unless the thermoelements are cold.

United States Patent Cohen et a1.

SETTING AND TRIGGERING DEVICE FOR THERMAL RELAY Inventors: Jacques Cohen, Courbevoie; Claude Zwingle, Argenteuil, both of France Assignee: La Telemecanique Electrique, Nanterre, France Filed: Jan. 15, 1973 Appl. No.1 323,581

Foreign Application Priority Data Jan. 14, 1972 France 72.01368 US. Cl 337/132, 337/66, 337/72 Int. Cl. H0lh 61/00 Field of Search 337/52, 49, 59, 62, 64,

References Cited UNITED STATES PATENTS 5/1924 Donle 337/72 X 9/1936 Atwood 337/49 9/1960 Ellenberger 337/66 1 Oct. 1, 1974 3,217,125 11/1965 Brackett 337/64 3,413,583 11/1968 Clark et a1... 3,495,203 2/1970 Neubauer 3,675,177 7/1972 Ellenberger 337/66 FOREIGN PATENTS OR APPLICATIONS 19,325 8/1956 Germany 337/66 708,972 8/1941 Germany 337/66 1,463,369 12/1968 Germany 337/66 Primary ExaminerA. T. Grimley Attorney, Agent, or Firm-William Anthony Drucker 5 7 ABSTRACT A thermal relay designed to control the power supply circuit of a contactor, said thermal relay comprising movable contacts cooperating with stationary contacts, a triggering slide released by thermoelements for displacing the movable contacts to open the circuit in case of excessive current flow and a hand control, controlling the slide and the movable contacts for opening or closing the circuit. The slide cannot be reset in proper position for closing the circuits unless the thermoelements are cold.

2 Claims, 4 Drawing Figures PATENTEDOBTI W I 3.839.691

sum EM 2 FIG. 3

FICAr SETTING AND TRIGGERING DEVICE FOR THERMAL RELAY The invention relates to a thermal relay designed to cut off the feed to a contactor, comprising a set of mobile contacts which may be made to open either by the intervention of a triggering device released when thermoel ements are traversed by too strong a current or by means of a manual control, which moreover serves to re-set the triggering device.

Such thermal relays are in particular used to protect polyphase instruments fed by a contactor, in case of overloading or unbalanced phases.

In this type of thermal relay, it is important to make it impossible for the contacts to close and the triggering mechanism to be re-set so long as the thermal conditions of the thermoelements, which translate the thermal state of the instrument consuming current, have not returned to a normal value, failing which manual pressure on the re-set button would aggravate the conditions which have led to the cut-off.

Already known are thermal relays of the type mentioned above, for example in US. Pat. No. 3,193,647 of Beaudoin et al., wherein the fixed contacts can be moved when the strength of the current consumed by an instrument exceeds a pre-selected value. One of the disadvantages of this type of instrument is that the fixed contacts have to be connected by means of braided wires to the connecting terminals to allow them to move. Another disadvantage is due to the fact that the mobile equipment which will cause the fixed contacts to, move is permanently on load when the contacts are closed, which reduces the instruments sensitivity.

The invention consequently proposed to provide a triggering and resetting system wherein the mobile contacts can only resume their closed position against absolutely fixed contacts when the triggering device has returned to a stable position corresponding to a satisfactory thermal condition.

In accordance with the invention, this result is achieved by the fact that operation of the manual setting component produces, on the one hand, the cooperation of a first part connected thereto to cause the mobile contacts to move away, and on the other hand, the cooperation of a second part connected thereto to move a triggering slide to a position where it can be retained by a lock connected to the thermoelements, while the release of the manual setting component ensures that the contacts are kept in an open position for a travel exceeding that which is necessary for said slide to connect with the lock and also exceeding that which is necessary for said slide, in case of non-locking, to cause a further withdrawal of the contacts.

In accordance with an advantageous embodiment of the invention, the mobile contacts are positioned on a contact-holder one heel of which can be moved by a bearing surface of the slide towards a first resilient component which tends to apply it to the fixed contacts and one end of which cooperates with a first inclined plane, constituting the first part, and situated at the end of the setting component, while a second inclined plane of the latter, constituting the second part, cooperates with the slide to allow the movement of the bearing surface towards the heel when the manual setting component is released, under the influence of a second resilient part whose strength exceeds that of the first resilient part. V

A better understanding of the invention will be obtained from the description which represents a nonlimiting example of embodiment of the invention, and the figures which provide the following illustrations:

FIG. 1 shows the thermal relay in its working position;

FIG. 2 shows the same instrument in its at rest" position;

FIGS. 3 and 4 show two successive stages of the setting procedure.

In FIG. 1, the thermal relay is in the working position, i.e., the setting component 1 is at rest, the mobile contacts 24, 27 carried by a bridge 23 are applied to the fixed contacts 26, 28 by a resilient part represented by the spring 22 and the triggering device represented by the slide 10 is hooked by its lip 12 on to the lock 16 whose position corresponds to thermoelements in a cold state.

The setting component 1 is normally recalled in the direction of the arrow F 1 by a spring 5 whose end hooks into the housing 8 while the slide is subjected to the action of a spring 15 which tends to move it in the direction of the arrow F In the embodiment illustrated in the figures, the springs 5 and 15 are in fact the ends of the same torsional spring mounted on a cylindrical support 6.

The figure shows that the contact bridge 23 is placed in a housing 25 formed in a contact-holder 20 with a rounded end 21 and a heel 29. This contact-holder is subjected to the action of the spring 22 to effect a movement in direction F when the heel 29 or the end 21 are not in contact with an obstacle.

The movement in question is guided by a groove 13 made in the triggering slide 10 and can take place freely so long as the heel 29 is not applied against the bearing surface 14 of the slide.

As the latter is mobile in the direction of the arrow F it can therefore carry the contact-holder 20 along with it under the effect of the spring 15 which exerts,

through the housing 7, a thrust exceeding that which is developed by the spring 22.

The slide also has a surface 11 which is inclined in relation to the direction of movement F and consequently, also inclined in relation to the direction F which is perpendicular to F The setting component 1 is positioned in such a way that a first part belonging thereto, represented by the inclined plane 3 and the bearing surface 4, can cooperate with the end 21 of the contact-holder when the device is actuated in the direction of the arrow F while a second part represented by the inclined plane 2 can cooperate with the inclined surface 11 belonging to the slide 10, in the same movement.

The position in which the various components are, shows that the triggering of the setting component 1 towards P, will cause the slide to recoil slightly in the direction F 3 and the contact-holder to make a larger recoil movement in the direction F separating the fixed and mobile contacts as shown in FIG. 4.

The setting component, which subsequently, when the electroelements are cold, only acts as a switch, will be used in this way when it is wished to de-excite the contactor whose coil feed circuit is in series with the contacts 26, 24, 27, 28.

When the strength of the current consumed by an instrument fed by means of the contactor is going to become too high, the thermoelements will change shape to move the lock 16 in the direction F and consequently move the slide in the direction F under the action of the spring 15, bringing about the opening of the contacts due to the thrust of 14 on the heel 29 and the placing of the various components in the at rest position shown in FIG. 2.

Besides the triggering function which has just been accomplished, the thermal relay also has to ensure that the closing of the contacts can only occur when the thermal conditions of the thermoelements, which translate the thermal condition of the consuming instrument, have resumed their normal state. Any operation of the setting component must therefore have no effect on the contacts so long as the slide 10 cannot be retained, held by the lock 16.

FIGS. 3 and 4 show successive stages of a procedure for re-setting the contacts.

When, from the at rest position shown in FIG. 2, the setting component is moved in the direction F the situation shown in FIG. 3 will first of all arise, which corresponds to a movement of the slide 10 in the direction F and decompression of the spring 22 due to a slight movement of the contact-holder in the same direction.

Further movement of this part is now prevented by the cooperation of the inclined plane 3 then the surface 4 with its end 21; the result is that the contacts cannot close during the setting procedure and the gap d will continue to increase. However, the movement of the slide is insufficient for the lip 12 to arrive opposite the lock 16.

In FIG. 4, the movement of the slide has become sufficient for the lock 16 to be able to grip the lip 12 when the thermoelements are cool. If, however, the lock has remained in the position corresponding to hot thermoelements indicated by 16, the contacts, which can only close when the setting component is released in direction F will be prevented from closing since the movement d necessary for such closing is greater than the distance d, which separates the heel 29 from the slide and this distance continues to decrease as and when the setting component 1 moves towards the top of the figure.

In other words, the upward travel of the button which is to allow the contact-holder to move to the closed po sition, is greater than that which is necessary for the slide to apply a further recoil to the contact-holder in the direction F this travel also exceeds that which is necessary for the slide to remain hooked on the lock,

failing which the contacts could not close.

The example of embodiment shown in the figure is in no way limitative, as the contact-holder and the slide could be arranged so as to be guided separately. The nature of their movements could also be modified and become circular. Similarly, the parts of the setting component cooperating with the slide and with the contactholder can be associated with intermediary components to change the direction of movement.

We claim:

1. A thermal relay comprising:

a. a movable contact holder (20) including a stud (29) and a thrust surface (21), and provided with mobile contacts (24,27), which cooperate with fixed contacts (26,28) when the contact holder is subjected to the action of a first resilient element (22);

b. a lock (16) connected to a thermosensitive element carrying electric current;

c. a slide (10) having a hook (12) and a bearing (14), which is operable in either a first position in which the hook (12) is applied, through the force of a second resilient element (15) against the lock (16) and in which the bearing (14) is located a distance from the stud (29); or in a second position in which the hook is no longer applied against the lock owing to deformation of the thermosensitive elements and in which the bearing (14) forces the stud (29) of the contact holder (20) against said first resilient element (22), said slide also having a ramp (1]) inclined in relation to the direction of movement of the slide; and

d. a manual operating device (1) including a first ramp (2) which when actuated cooperates with the ramp (11) to move the slide into a first position and a second ramp (3) which cooperates with the thrust surface (21) to move the contact holder and separate the fixed and mobile contacts (26, 28 and 24, 27).

2. In a thermal relay according to claim 1, the improvement in which: the first and second ramps of the manual operating device (1) include surfaces (3,4) inclined in opposite directions located between the ramp (11) and the thrust surface (21) to cause oppositely directed movements of the slide (10) in relation to the contact holder (20), the latter being guided in a groove (13) of the slide (10). 

1. A thermal relay comprising: a. a movable contact holder (20) including a stud (29) and a thrust surface (21), and provided with mobile contacts (24,27), which cooperate with fixed contacts (26,28) when the contact holder is subjected to the action of a first resilient element (22); b. a lock (16) connected to a thermosensitive element carrying electric current; c. a slide (10) having a hook (12) and a bearing (14), which is operable in either a first position in which the hook (12) is applied, through the force of a second resilient element (15) against the lock (16) and in which the bearing (14) is located a distance from the stud (29); or in a second position in which the hook is no longer applied against the lock owing to deformation of the thermosensitive elements and in which the bearing (14) forces the stud (29) of the contact holder (20) against said first resilient element (22), said slide also having a ramp (11) inclinEd in relation to the direction of movement of the slide; and d. a manual operating device (1) including a first ramp (2) which when actuated cooperates with the ramp (11) to move the slide into a first position and a second ramp (3) which cooperates with the thrust surface (21) to move the contact holder and separate the fixed and mobile contacts (26, 28 and 24, 27).
 2. In a thermal relay according to claim 1, the improvement in which: the first and second ramps of the manual operating device (1) include surfaces (3,4) inclined in opposite directions located between the ramp (11) and the thrust surface (21) to cause oppositely directed movements of the slide (10) in relation to the contact holder (20), the latter being guided in a groove (13) of the slide (10). 